Composition comprising esters of lignin and oil or fatty acids

ABSTRACT

The present invention relates to a composition comprising a carrier liquid and lignin or lignin derivatives; wherein at least one of the hydroxyl groups of the biomass have been substituted with ester groups and wherein the carrier liquid is a gas oil. The composition may be used for preparing fuels or lubricants.

FIELD OF THE INVENTION

The present invention relates to a composition with a high lignincontent in a fatty acid or oil where the lignin has been functionalizedwith ester groups and a method of preparing said composition where theesterification step may be performed in the fatty acid or oil. Thecomposition may be used to produce fuels.

BACKGROUND

There is an increasing interest in using biomass as a source for fuelproduction. Biomass includes, but is not limited to, plant parts,fruits, vegetables, processing waste, wood chips, chaff, grain, grasses,corn, corn husks, weeds, aquatic plants, hay, paper, paper products,recycled paper and paper products, lignocellulosic material, lignin andany cellulose containing biological material or material of biologicalorigin.

An important component of biomass is the lignin present in the solidportions of the biomass. Lignin comprises chains of aromatic andoxygenate constituents forming larger molecules that are not easilytreated. A major reason for difficulty in treating the lignin is theinability to disperse the lignin for contact with catalysts that canbreak the lignin down.

Lignin is one of the most abundant natural polymers on earth. One commonway of obtaining lignin is by separation from wood during pulpingprocesses. Only a small amount (1-2%) is utilized in specialty productswhereas the rest primary serves as fuel. Even if burning lignin is avaluable way to reduce usage of fossil fuel, lignin has significantpotential as raw material for the sustainable production of chemicalsand liquid fuels.

Various lignins differ structurally depending on raw material source andsubsequent processing, but one common feature is a backbone consistingof various substituted phenyl propane units that are bound to each othervia aryl ether or carbon-carbon linkages. They are typically substitutedwith methoxy groups and the phenolic and aliphatic hydroxyl groupsprovide sites for e.g. further functionalization. Lignin is known tohave a low ability to adsorb water compared to for example thehydrophilic cellulose.

Today lignin may be used as a component in for example pellet fuel as abinder but it may also be used as an energy source due to its highenergy content. Lignin has higher energy content than cellulose orhemicelluloses and one gram of lignin has on average 2.27 kJ, which is30% more than the energy content of cellulosic carbohydrate. The energycontent of lignin is similar to that of coal. Today, due to its fuelvalue lignin that has been removed using the Kraft process, sulphateprocess, in a pulp or paper mill, is usually burned in order to provideenergy to run the production process and to recover the chemicals fromthe cooking liquor.

There are several ways of separating lignin from black or red liquorobtained after separating the cellulose fibres in the Kraft or sulphiteprocess respectively, during the production processes. One of the mostcommon strategies is ultra-filtration. Lignoboost® is a separationprocess developed by Innventia AB and the process has been shown toincrease the lignin yield using less sulphuric acid. In the Lignoboost®process, black liquor from the production processes is taken and thelignin is precipitated through the addition and reaction with acid,usually carbon dioxide (CO₂), and the lignin is then filtered off. Thelignin filter cake is then re-dispersed and acidified, usually usingsulphuric acid, and the obtained slurry is then filtered and washedusing displacement washing. The lignin is usually then dried andpulverized in order to make it suitable for lime kiln burners or beforepelletizing it into pellet fuel.

Biofuel, such as biogasoline and biodiesel, is a fuel in which theenergy is mainly derived from biomass material or gases such as wood,corn, sugarcane, animal fat, vegetable oils and so on. However thebiofuel industries are struggling with issues like food vs fuel debate,efficiency and the general supply of raw material. At the same time thepulp or paper making industries produces huge amounts of lignin which isoften, as described above, only burned in the mill. Two commonstrategies for exploring biomass as a fuel or fuel component are to usepyrolysis oils or hydrogenated lignin.

In order to make lignin more useful one has to solve the problem withthe low solubility of lignin in organic solvents. One drawback of usinglignin as a source for fuel production is the issue of providing ligninor lignin derivatives in a form suitable for hydrotreaters or crackers.The problem is that lignin is not soluble in oils or fatty acids whichis, if not necessary, highly wanted.

Prior art provides various strategies for degrading lignin into smallunits or molecules in order to prepare lignin derivatives that may beprocessed. These strategies include hydrogenation, dexoygenation andacid catalyst hydrolysis. WO2011003029 relates to a method for catalyticcleavage of carbon-carbon bonds and carbon-oxygen bonds in lignin.US20130025191 relates to a depolymerisation and deoxygenation methodwhere lignin is treated with hydrogen together with a catalyst in anaromatic containing solvent. All these strategies relates to methodswhere the degradation is performed prior to eventual mixing in fattyacids or oils. WO2008157164 discloses an alternative strategy where afirst dispersion agent is used to form a biomass suspension to obtain abetter contact with the catalyst. These strategies usually also requiresisolation of the degradation products in order to separate them fromunwanted reagents such as solvents or catalysts.

The economic benefits of producing fuels from biomass depend for exampleon an efficient process for preparing the lignin and on the preparationof the lignin or lignin derivatives so that the fuel production is asefficient as possible. For example the amount of oxygen should be as lowas possible and the number of preparation steps should be as few aspossible.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the drawbacks ofsolubility of the prior art. The present invention relates to acomposition comprising a high content of lignin or lignin derivatives ina fatty acid, esterified fatty acid or oil and optionally an organicsolvent as well. In order to obtain a high content of lignin it havebeen functionalized or modified by esterification of the hydroxylgroups. One application for the composition may be as a raw material forfuel production or for the preparation of lubricating oils.

The present invention facilitates the preparation of a compositionsuitable for fuel production which does not require pre-preparationsteps such as degradation and isolation steps. Instead thefunctionalization of the biomass may be prepared in the carrier liquidin situ. Furthermore, the composition according to the present inventionmay be used as it is to prepare fuel or it may be added into to aproduction stream at a refinery. The composition may be mixed withwell-known carrier liquids (oils for example).

In the widest aspect the present invention relates to compositioncomprising a carrier liquid and lignin or lignin derivatives solubilizedin said carrier liquid; wherein at least one of the hydroxyl groups ofthe lignin or lignin derivatives have been substituted with ester groupsforming esterified lignin or lignin derivatives.

The hydroxyl groups of the lignin or lignin derivative may besubstituted with ester groups of a fatty acid, preferably an unsaturatedfatty acid.

In a second aspect the present invention relates to a method ofpreparing the composition according to the present invention comprising:

-   -   a. Providing a carrier liquid,    -   b. Providing lignin or lignin derivatives;    -   c. Providing an esterification agent or, a fatty acid and an        esterification agent, and optionally a catalyst;    -   d. Mixing the components of step b and c;    -   e. Heating the mixture to at least 80° C.;    -   f. Letting the components react in order to obtain esterified        biomass material;    -   g. Optionally isolating the esterified biomass material; and    -   h. Mixing the esterified biomass material with the carrier        liquid.

In a third aspect the present invention relates to a product obtainableby the method of the present invention.

In a fourth aspect the present invention relates to the use of themethod to prepare compositions for fuel production.

In a fifth aspect the present invention relates to a method of makingfuel by treating the composition according to the present invention in ahydrotreater or a catalytic cracker.

In a sixth aspect the present invention relates to a fuel obtained fromthe composition according to the present invention.

In a seventh aspect the present invention relates to the use of thecomposition to prepare fine chemicals such as aromatic compounds.

BRIEF DESCRIPTION OF FIGURES

FIG. 1, table of solubility for esterified lignin in various solventsand carrier liquids (values given as weight % esterified lignin).

FIGS. 2A and 2B, table of solubility for esterified lignin in varioussolvents and carrier liquids (values given as weight % esterifiedlignin).

(EA=ethyl acetate, EtOH=ethanol, MeTHF=methylated tetrahydrofuran,CPME=cyclocpentyl methyl ether, iPrOH=iso-propanol, RTD=tall oil,LGO=light gas oil, CF=membrane filtered lignin, LGTPA=acid precipitatedlignin from black liquor dried to 95% dry weight and GM63=ligninchemically reduced using the method according to WO2012/121659)

FIG. 3, GPC of esterified lignin according to the present invention.

FIG. 4, GPC of esterified lignin according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention presents a composition for use in refineryprocesses for the production of various fuels.

In the present application the term “lignin” means a polymer comprisingcoumaryl alcohol, coniferyl alcohol and sinapyl alcohol monomers.

In the present application the term “lignin derivative” means moleculesor polymers derived from lignin. In the present application “ligninderivative” and “molecules or polymers derived from lignin” are usedinterchangeably. These molecules or polymers may be a result of chemicalmodification or degradation of lignin or a lignin source, for examplewhen treating black or red liquor in order to precipitate or separatelignin. The number average molecular weight (M_(n)) of the ligninderivative may be 500 g/mol or higher, or 800 g/mol or higher, forexample 500-2000 g/mol, or 700-1500 g/mol.

In the present application the term “carrier liquid” means a liquidselected from fatty acids or mixture of fatty acids, esterified fattyacids, rosin acid, crude oil, mineral oil and hydrocarbon oils ormixtures thereof.

In the present invention the term “oil” means a nonpolar chemicalsubstance that is a viscous liquid at ambient temperature and is bothhydrophobic and lipophilic.

In the present application the terms “red liquor” and “brown liquor”denote the same liquor.

When calculating number of repeating units and equivalents one repeatingunit of lignin is assumed to be 180 Da. The degree substitution iscalculated from 1H NMR using an internal standard, and 1-eq substitutiondegree is defined as a presence of one covalently attached acyl groupper one lignin monomer. For example to achieve close to completesubstitution we have used a twofold excess of acylating agent per onelignin monomer, which afforded substitution degrees ranging from 0.91 to1.43 equivalents

For a substance to be processed in a refinery such as an oil refinery orbio oil refinery, the substance needs to be in liquid phase. Either thesubstance is in liquid phase at a given temperature (usually below 80°C.) or the substance is solvated in a liquid. In the present patentapplication, such liquid will be given the term carrier liquid. Thepresent invention presents a composition and a method of preparing saidcomposition where the composition comprises a biomass material,preferably lignin or lignin derivatives, where the biomass material isin liquid phase and may be processed in a refinery. The presentinvention makes it easier or even facilitates production of fuel frombiomass material.

In order to obtain lignin biomass may be treated in any suitable wayknown to a person skilled in the art. The biomass may be treated withpulping processes or organosolv processes for example. Biomass includes,but is not limited to wood, fruits, vegetables, processing waste, chaff,grain, grasses, corn, corn husks, weeds, aquatic plants, hay, paper,paper products, recycled paper, shell, brown coal, algae, straw, bark ornut shells, lignocellulosic material, lignin and any cellulosecontaining biological material or material of biological origin. In oneembodiment the biomass is wood, preferably particulate wood such as sawdust or wood chips. The wood may be any kind of wood, hard or soft wood,coniferous tree or broad-leaf tree. A non-limiting list of woods wouldbe pine, birch, spruce, maple, ash, mountain ash, redwood, alder, elm,oak, larch, yew, chestnut, olive, cypress, banyan, sycamore, cherry,apple, pear, hawthorn, magnolia, sequoia, walnut, karri, coolabah andbeech.

It is preferred that the biomass contains as much lignin as possible.The Kappa number estimates the amount of chemicals required duringbleaching of wood pulp in order to obtain a pulp with a given degree ofwhiteness. Since the amount of bleach needed is related to the lignincontent of the pulp, the Kappa number can be used to monitor theeffectiveness of the lignin-extraction phase of the pulping process. Itis approximately proportional to the residual lignin content of thepulp.K≈c*l

K: Kappa number; c: constant≈6.57 (dependent on process and wood); l:lignin content in percent. The Kappa number is determined by ISO302:2004. The kappa number may be 20 or higher, or 40 or higher, or 60or higher. In one embodiment the kappa number is 10-100.

Biomass materials and derivatives thereof often have a general formulaof C_(x)H_(y)O_(z) where the ratio z/x depends on origin, part of theplant and also processes of the biomass material, and where x and y eachare ≥1 and z≥0. Preferably x is ≥2, or more preferably x is ≥3, or morepreferably x is ≥6; z is preferably ≥1, or ≥2. In one embodiment x is≤20, in another embodiment x is ≤15, and in yet another embodiment x is≤11. In one embodiment z is ≤10 and in another embodiment z is ≤5. Thebiomass material may comprise other heteroatoms such as S or N.

The lignin may be in the form of a mixture of biomass materials andderivatives thereof. In one embodiment the lignin is in the form ofblack or red liquor. Black and red liquor contains cellulose, hemicellulose and lignin and derivatives thereof.

The composition according to the present invention may comprise black orred liquor, or lignin or lignin derivatives obtained from black or redliquor.

Black liquor comprises four main groups of organic substances, around30-45 weight % ligneous material, 25-35 weight % saccharine acids, about10 weight % formic and acetic acid, 3-5 weight % extractives, about 1weight % methanol, and many inorganic elements and sulphur. The exactcomposition of the liquor varies and depends on the cooking conditionsin the production process and the feedstock. Red liquor comprises theions from the sulfite process (calcium, sodium, magnesium or ammonium),sulfonated lignin, hemicellulose and low molecular resins.

The lignin may be Kraft lignin, sulfonated lignin, Lignoboost® lignin,precipitated lignin, filtrated lignin, acetosolv lignin or organosolvlignin. In one embodiment the lignin is Kraft lignin, acetosolv ligninor organosolv lignin. In another embodiment the lignin is Kraft lignin.In another embodiment the lignin is organosolv lignin. In anotherembodiment the lignin or lignin derivatives obtained as residualmaterial from ethanol production. The lignin may be in particulate formwith a particle size of 5 mm or less, or 1 mm or less.

Lignin is not soluble in most organic solvents, fatty acids or oils.Instead prior art have presented various techniques to depolymerize andcovert the depolymerized lignin into components soluble in the wantedmedia.

The number average molecular weight (mass) (M_(n)) of the lignin may be30,000 g/mol or less, such as not more than 20,000 g/mol, or not morethan 10,000 g/mol, or not more than 5,000 g/mol, or not more than 2,000g/mol, or not more than 1,000 g/mol, or higher than 800 g/mol, or higherthan 950 g/mol. In one embodiment the number average molecular weight ofthe lignin is between 150 and 4,000 g/mol, or between 300 and 1,000g/mol.

The esterified lignin or lignin derivative may have a number averagemolecular weight (M_(n)) of 300 g/mol or more, or 1,000 g/mol or more,or 2,000 g/mol or more, or 5,000 g/mol or more, or 8,000 g/mol or morebut less than 10,000 g/mol. In one embodiment the number averagemolecular weight (M_(n)) is 1,000 to 6,000 g/mol, or 2,000 g/mol to4,000 g/mol.

The purpose of the carrier liquid is to carry the wanted substrate orsolution into the reactor without reacting or in any other way affectingthe substrate or solution. Therefore, in one embodiment of the presentapplication the carrier liquid is an inert hydrocarbon with a highboiling point, preferably at least 150° C.

The carrier liquid should preferably be suitable for a hydrotreater or acatalytic cracker (cat cracker), preferably a liquid suitable for bothhydrotreater and catalytic cracker. Hydrotreating and catalytic crackingare steps in the refinery process where the sulfur, oxygen and nitrogencontents of the oil is reduced and where high-boiling, high molecularweight hydrocarbons are converted into gasoline, diesel and gases. Inone embodiment the carrier liquid is a fatty acid or a mixture of fattyacids. In another embodiment the carrier liquid is esterified fattyacids such as FAME (fatty acid methyl ester). The fatty acid used in thepresent invention (as fatty acid or as esterified fatty acid) may be aC4 or longer fatty acid, or C8 or longer fatty acid, or a C14 or longerfatty acid. In one embodiment the fatty acid or the mixture of the fattyacids or the esterified fatty acid comprises unsaturated fatty acids,preferably at a concentration of more than 25 wt %, or more than 50 wt%. In one embodiment the carrier liquid is a tall oil. In one embodimentthe carrier liquid is a crude oil. In another embodiment the carrierliquid is a hydrocarbon oil or a mineral oil. In yet another embodimentthe carrier liquid is a mixture of a fatty acid and crude oil, or ahydrocarbon oil or a mineral oil. The ratio in said mixture may be 5-90wt % (of the total weight of the carrier liquid) fatty acid oresterified fatty acid and 10-95 wt % of hydrocarbon oil or mineral oil,for example 10-40 wt % fatty acid or esterified fatty acid and 60-90 wt% of hydrocarbon oil or mineral oil. The purpose of using esterifiedfatty acid instead of fatty acid is to limit the corrosive properties ofthe acid groups of the fatty acid. In one embodiment at least 80% of theacid groups of the fatty acid is esterified, preferably at least 95%.

When the carrier liquid is or comprises a crude oil, hydrocarbon oil ormineral oil the oil needs to be in liquid phase below 80° C. andpreferably have boiling points of 177-371° C. These hydrocarbon oilsinclude different types of or gas oils and likewise e.g. Full RangeStraight Run Middle Distillates, Hydrotreated, Middle Distillate, LightCatalytic Cracked Distillate, Naphtha full-range straight-rundistillates, hydrodesulfurized full-range distillates, solvent-dewaxedstraight-range distillates, straight-run middle sulfenylated, Naphthaclay-treated full-range straight run distillates full-range atm,hydrotreated full-range distillates, straight-run light distillatesheavy straight-run, straight-run middle-run, Naphtha (shale oil),hydrocracked, full-range straight run (example of but not restricted toCAS nr: 68476-30-2, 68814-87-9, 74742-46-7, 64741-59-9, 64741-44-2,64741-42-0, 101316-57-8, 101316-58-9, 91722-55-3, 91995-58-3,68527-21-9, 128683-26-1, 91995-46-9, 68410-05-9, 68915-96-8,128683-27-2, 195459-19-9). Moreover substances can be solvated inlighter hydrocarbon fractions such as organic solvents e.g. mesitylene,toluene, benzene, petroleum ether, octanes, nonanes, decanes and alsoisomerized derivatives of these compounds or mixtures thereof (CAS nr:108-88-3, 108-67-8, 71-43-2, 8032-32-4, 111-65-9, 111-84-2, 124-18-5).

When the carrier liquid is a fatty acid (second fatty acid) said fattyacid may be but is not limited to C6-C18 fatty acids, saturated orunsaturated, or a mixtures of C2-C18 fatty acids. The fatty acid mayfurther be methylated or ethylated. The second fatty acid may be avegetable fatty acid such as a tall oil fatty acid (TOFA), or olive oil,soybean oil, corn oil, hemp or coconut oil, but can also be derived fromanimal fats. In one embodiment the first and the second fatty acid arethe same.

In one embodiment the carrier liquid is a second fatty acid or a mixtureof second fatty acids or a mixture comprising a second fatty acid and ahydrocarbon oil. In one embodiment the second fatty acid is anunsaturated fatty acid or is a mixture of fatty acids in which themixture contains unsaturated fatty acids. In one embodiment the firstand the second fatty acids are the same, for example tall oils.

The composition may comprise 10-99 weight % of carrier liquid, such as20 weight % or more, or 40 weight % or more, or 60 weight % or more, or80 weight % or more, or 99 weight % or less, or 85 weight % or less. Inone embodiment the amount of carrier liquid is 60-90 weight % such as65-85 weight %.

The composition may further comprise an organic solvent, or a mixture oforganic solvents. The composition may comprise a mixture of an organicsolvent and a fatty acid or esterified fatty acid and/or an oil. Theorganic solvent may be but is not limited to oxygenates such as analcohol, ester, ketone, ether, aldehydes, furane or furfural basedsolvent. Preferred solvents are C1-C10 alcohols, C1-C10 aldehydes,C2-C15 ketones, C2-C10 ethers, and C2-C10 esters. A non-limiting list ofsolvents is methanol, ethanol, propanol, isopropanol, glycerol, andbutyl ether such as tert-butyl methyl ether; diethyl ether, diglyme,diisopropyl ether, dimethoxyethane, diethylene glycol, diethyl ether,polyethylene glycol, 1,4-dioxane and tetrahydrofuran, methylatedtetrahydrofuran, mesityl oxide, furfural, isophorone. Preferred C2-C10esters are organic esters, aromatic or non-aromatic esters, examples ofesters are benzyl benzoate, various acetates such as methyl acetate,ethyl acetate, cyclopentyl methyl ether and butyl acetate, variouslactates such as ethyl lactates. Solvents that are similar to or may beconverted into fuel or petrol are interesting when the composition is tobe used for fuel preparation. Such solvents could be ketones oraldehydes. In one embodiment the solvent is a C2-C15 ketone such as aC4-C12 ketone or a C6-C8 ketone. In one embodiment the solvent is aC1-C10 aldehyde such as a C4-C9 aldehyde or C6-C8 aldehyde. In oneembodiment the solvent is a mixture of a C2-C15 ketone and a C1-C10aldehyde. In one embodiment the solvent is mesityl oxide. In oneembodiment the solvent is acetone. In one embodiment the solvent isacetophenone. In one embodiment the solvent is pentanone. In oneembodiment the solvent is ethyl isopropyl ketone. In one embodiment thesolvent is isophorone. In one embodiment the organic solvent is anaromatic aldehyde or a mixture containing an aromatic aldehyde forexample furfural. In one embodiment the solvent comprises furfural orfurfuryl alcohol. In one embodiment the solvent is benzaldehyde. In oneembodiment the solvent is ethyl acetate. In one embodiment the solventis ethanol. In one embodiment the solvent is methanol. In one embodimentthe solvent is isopropanol. In one embodiment the solvent is solketal.In one embodiment the solvent is tetrahydrofuran or methylatedtetrahydrofuran. In one embodiment the solvent is 1,4-dioxane.

In one embodiment the solvent comprises a combination of C1-C10alcohols, C1-C10 ethers and C1-C10 esters. In one embodiment the solventcomprises two C1-C10 alcohols for example ethanol and glycerol, and inanother embodiment the solvent comprises propanol and glycerol. In oneembodiment the solvent comprises polyethylene glycol and a C1-C10alcohol. When the solvent is a mixture of an organic solvent and waterthe mixture may contain methanol and water, ethanol and water,isopropanol and water or ethyl acetate and water, preferably ethanol andwater, isopropanol and water and ethyl acetate and water.

In one embodiment the amount of organic solvent is 1-99 weight %. In oneembodiment the amount of organic solvent is 70 weight % or less, or 40weight % or less, or 20 weight % or less, or 10 weight % or less, or 5weight % or less or 2 weight % or less of the total weight of thecomposition. In one embodiment the amount of solvent is 10-60 weight %,or 20-50 weight %. In some applications the amount of organic solventshould be as low as possible.

The present inventors found that by esterifying the hydroxyl groups ofthe lignin or lignin derivatives the solubility of the lignin increaseddrastically. The composition according to the present invention may beprepared by first preparing the esterified lignin or lignin derivativeand then mixing said esterified lignin with the carrier liquid orsolvent. The esterified lignin may be isolated from the esterificationreaction mixture or the esterified lignin is left in the reactionmixture when mixed with the carrier liquid or solvent. Theesterification of the lignin may also be performed in situ, i.e. in thecarrier liquid or solvent. Then the lignin, the esterification agent or,the first fatty acid and an esterification agent, and the carrier liquid(or solvent) and optionally a catalyst are mixed to form a slurry ormixture. The slurry or mixture is then preferably heated between 50° C.and 350° C., such as 50° C. or higher, or 80° C. or higher or 100° C. orhigher, or 120° C. or higher, or 150° C. or higher, but not higher than350° C., or 250° C. or lower, or 200° C. or lower, or 180° C. or lower.The esterification of the lignin occurs in the carrier liquid leaving ahomogenous composition of carrier liquid and esterified biomass, andoptionally catalyst. The catalyst and any other unwanted components maybe removed afterwards. The mixing can be done by stirring or shaking orin any other suitable way. When the esterification is performed in acarrier liquid comprising a first fatty acid and together with anesterification agent such as an anhydride the obtained esterified ligninis believed to comprise ester groups derived from the anhydride alonebut also ester groups derived from an anhydride bond to a first fattyacid. In order to remove any acid groups of remaining fatty acids orfatty acids in the carrier liquid any suitable method may be used. Forexample an alcohol such as methanol may be added.

The esterified lignin may be isolated by precipitation in for examplehexane or water. When the degree of substitution (esterification) ishigh, for example 50% or more, and the lignin is substituted with C2-C4ester groups the esterified lignin may be treated with a base forexample NaHCO₃ (aq) before precipitation in order to remove free acid.When the lignin is substituted with longer ester groups celite may beused. The esterified lignin according to the present invention may alsobe separated from metals and other additives or catalysts by simplyrinsing the lignin in an aqueous solution or water. For many industries,for example the fuel refinery industry processing lignin, the amount ofmetals should be as low as possible since metals may damage themachinery or disturb the process. By forming the ester groups in situ,insoluble biomass may become soluble. For example lignin substitutedwith acetic ester groups is not dissolved in tall oil. However whenforming the acetic ester in the tall oil the obtained homogenous mixturecomprises 32 wt % of the formed lignin ester, see example 29.

The esterification agent may be a carboxylic acid or an anhydride. Theesterification agents preferably contain an unsaturated bond.Non-limiting examples of carboxylic acids are fatty acids or C2-C42carboxylic esters, preferably C4 to C22 such as C18, and non-limitingexamples of anhydrides are C4 to C42 anhydrides. The ester groups maytherefore be C2-C42 or C4-C42 preferably C4-C22 such as C18. Estergroups with longer chains tend to be more easily dissolved, especiallyin carrier liquids, and increases the C/O ratio. In one embodiment theester groups is one or more C2-C42 groups, such as C6-C18 groups. Still,especially when using organic solvents, the ester groups may be C2-C18,or C2-C12, C12-C18 or C2-C6 since it was found that the solubilityincreased substantially even when using shorter ester groups, FIGS. 1and 2. Another important factor is the availability and the cost of theesterification agent. The catalyst for the esterification may be anitrogen containing aromatic heterocycle such as N-methyl imidazole orpyridine, or the catalyst may be a metal acetylacetonate such asTiO(acac)₂ or Fe(acac)₃. In table 1 and 2 the content of esterifiedlignin in different organic solvents and carrier liquids are presented.

In one embodiment the composition comprises a first fatty acid or oiland lignin or lignin derivatives; wherein at least one of the hydroxylgroups of the lignin or lignin derivatives have been substituted withester groups of a second fatty acid, preferably an unsaturated secondfatty acid, forming esterified lignin or lignin derivatives.

The hydroxyl groups of lignin may be divided into aliphatic hydroxyls(ROH), condensed phenol (PhOH), phenol and acids. The degree ofsubstitution, i.e. the degree of hydroxyl groups that has been convertedinto ester groups, may be from 10% to 100%, for example 20% or more, 30%or more, or 40% or more, or 60% or more or 80% or more, or 99% or more,or 100%. It is also possible to have part of the lignin, or the hydroxylgroups on the lignin, being substituted with one type of ester group(for example C2-C6 ester groups) and another part substituted withanother type of ester group (for example C8-C18 ester groups). Forexample 10-40% of the hydroxyl groups may be substituted with acetylgroups and 60-90% of the hydroxyl groups may be substituted with a fattyacid, preferably C12 or longer ester groups. When the compositioncomprises an organic solvent the degree of substitution does not have tobe as high, for example 10-60% or 20-40%, in comparison when thecomposition comprises only a carrier liquid.

Lignin wherein the ester groups are unsaturated is oilier at roomtemperature while lignin substituted with a saturated ester group ismore solid or wax like material. By having the lignin in oil phase thereis no need to heat the lignin in order for it to dissolve in the wantedsolvent. In order to keep the wax like lignin in solution it needs to bekept at the elevated temperature (for example 70° C.) which makestransportation and stock keeping more costly. This issue is solved withthe present invention and instead the composition may be prepared atroom temperature.

Substituting the hydroxyl groups of the lignin increases the solubilityin organic solvents. The inventors found that even at low degree ofsubstitution (0.3 equivalents, 25% degree of substitution) the ligninbecomes soluble in ethyl acetate, methyl THF, cyclopentyl methyl etherand iso-propanol. For the lignin to be dissolved in an oil such as lightgas oil (LGO) the degree of substitution should be more than 30% forester groups of C8 and longer, preferably 50% or more. If the carrierliquid is a mixture of a fatty acid and an oil the esterified ligninbecomes more soluble. In one embodiment the composition is a one phasesystem.

The non-esterified groups may be capped for example with an anhydridesuch as acetic anhydride under common esterification conditions.

One advantage of the present invention is that a higher amount of ligninmay be dissolved in a carrier liquid. The amount of esterified lignin orlignin derivatives in the composition according to the present inventionmay be 1 weight % or more, or 2 weight % or more, 4 weight % or more, or5 weight % or more, or 7 weight % or more, or 10 weight % or more, or 12weight % or more, or 15 weight % or more, or 20 weight % or more, or 25weight % or more, or 30 weight % or more, or 40 weight % or more, or 50weight % or more, or 60 weight % or more, or 70 weight % or more, or 75weight % or more based on the total weight of the composition.

In one embodiment the lignin or lignin derivatives are dearomatized. Forexample the lignin or lignin derivatives are dearomatized to at least40%, or at least 50%, or at least 60%, or at least 70%, or at least 80%,or at least 90%, or at least 95%, or at least 99%.

The composition may further comprise at least one additive. The additivemay be any additive known to a person skilled in the art. In oneembodiment the additive may further enhance the dissolution of thelignin or lignin derivatives. The additive may have the function ofdissolving or breaking up inter molecular bonds between the ligninchains or the lignin derivatives. In one embodiment the additive is apolar compound or a salt.

When the method of the present invention is performed using black or redliquor the liquor may be pre-treated by evaporation, separation orfiltration or via chemical treatments such as the process describedbelow and further defined in WO2012/121659.

The biomass, or the lignin or lignin derivatives in the composition mayhave been treated with the process described in WO2012/121659 which ishereby incorporated by reference. The process relates to reduction of asubstrate wherein said substrate can be but is not limited to primary,secondary and tertiary benzylic or allylic alcohol, benzylic or allylicether, benzylic or allylic carbonyl, and benzylic or allylic ester, orolefins to the corresponding hydrocarbon. The substrate may be lignin orany other compound or polymer comprising said functional group, or blackor red liquor. A general method comprises adding a catalyst, atransition metal catalyst, to a reaction flask or container. Adding asolvent mixture of at least two solvents where one of the solvents iswater and a base. The mixture is then heated followed by addition of ahydrogen donor and the substrate to be reduced. In order to inhibitdisproportionation, a base or carbon dioxide should be added to thesolvent mixture and catalyst prior to addition of a hydrogen donor andthe substrate. The hydrogen donor may for example be formic acid or analcohol, it may even be hydrogen gas. The reduction is performed at atemperature of 40-100° C. In one embodiment the amount of base is notstoichiometric to the amount of the substrate. The separated lignin andlignin derivatives obtained from the reduction method may then be usedin the composition according to the present invention. In one embodimentthe lignin or lignin derivatives from the chemical reduction is furthertreated with filtration, ultra-filtration or cross-flowultra-filtration; or treated with acidification and separation such asthe Lignoboost® technique.

In another embodiment the composition of the present invention maycomprise lignin or lignin derivatives obtained through precipitation andseparation of lignin and lignin derivatives for example by acidificationand separation, such as filtration. Lignoboost® or any other similarseparation technique are examples of such technique and may be used. Theseparated lignin and lignin derivatives may then be used as the biomassmaterial in the composition according to the present invention. Inanother embodiment the separated lignin and lignin derivative mayfurther be chemically reduced using the method described above and inWO2012/121659.

Another method or a complimentary method for purifying or separatinglignin is through filtration, membrane-filtration, ultra-filtration orcross-flow ultra-filtration. The lignin may be separated in respect tosize through any of said filtration techniques. The lignin or ligninderivatives may also be separated in respect to size through adepolymerisation technique; this separation may be performed incombination with filtration, ultra-filtration or cross-flowultra-filtration. By using filtration, ultra-filtration or cross-flowultra-filtration on black or red liquor lignin or lignin derivativeswith molecular weights of 10,000 g/mol or less may be separated,preferably the separated lignin or lignin derivatives have a molecularweight of 2,000 g/mol or less, such as 1,000 g/mol or less. Theseparated lignin and lignin derivatives may then be used as the biomassmaterial in the composition according to the present invention. In oneembodiment the lignin and lignin derivatives obtained from saidfiltration may further be chemically reduced using the method describedabove and in WO2012/121659.

The composition according to the present invention may be used in arefinery process or as a pre-step to a refinery process for preparingfuel such as diesel and petrol, or diesel and petrol analogues; orbiogasoline or biodiesel; or fuel additives. The composition may furtherbe used to prepare lubricants, oils. For example synthetic oils withboiling point of at least 359° C.

The composition according to the present invention may also be used asan additive, for example as a concreted grinding aid, set retarder forcement, strengthener of cement, antioxidant, enhancer of thermalprotection, stabilizer in asphalt, emulsifying agent, fiberstrengthening additive, cross-linking agent, board binder,anti-corrosion additive, wear resistant additive, antifriction additive,binder, emulsifier or dispersing agent.

The composition may further be used to prepare foams, plastics, rubbersor paint. The esterified lignin may be used as a cross-linking or curingagent, or as a water absorption inhibitor or as a fluidization agent.Mechanical properties may also be enhanced by the use of thecomposition. The composition may further be used as a raw material forpreparing fine chemicals such as aromatic compounds using conventionaltechniques.

The composition may be added to surfaces to obtain dust control, or thecomposition may be used to prepare batteries.

EXAMPLES

In some of the examples below the following lignin types have been used.

Lignin type A1: acid precipitated lignin from black liquor

Lignin type A2: acid precipitated lignin from black liquor dried to 95%dry weight

Lignin type A3: hexyl ester of acid precipitated lignin from blackliquor

Lignin type B: filtered black liquor

Lignin type C: lignin chemically reduced using the method according toWO2012/121659

In the examples below the symbol “<” means that not all of the substratefor example lignin was dissolved.

Example 1

To a solution of ethyl acetate (0.1044 g) Lignin type A2-Ac-ester(0.1046 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 50 weight % of Lignin typeA2-Ac-ester was attained.

Example 2

To a solution of ethanol (0.0858 g) Lignin type A2-Ac-ester (0.1086 g)was added. The suspension was stirred under heating (70° C.). A pourablesolution at 70° C. comprising 56 weight % of Lignin type A2-Ac-ester wasattained.

Example 3

To a solution of acetone (0.0592 g) Lignin type A2-Ac-ester (0.1012 g)was added. The suspension was stirred under heating (70° C.). A pourablesolution at 70° C. comprising 63 weight % of Lignin type A2-Ac-ester wasattained.

Example 4

To a solution of polyethylene glycol (0.1372 g) Lignin type A2-Ac-ester(0.0986 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 42 weight % of Lignin typeA2-Ac-ester was attained.

Example 5

To a solution of glycerol (1.1634 g) Lignin type A2-Ac-ester (0.1032 g)was added. The suspension was stirred under heating (70° C.). A solutioncomprising <8 weight % of Lignin type A2-Ac-ester was attained.

Example 6

To a solution of 2-methyltetrahydrofuran (0.0865 g) Lignin typeA2-Ac-ester (0.0981 g) was added. The suspension was stirred underheating (70° C.). A pourable solution at 70° C. comprising 53 weight %of Lignin type A2-Ac-ester was attained.

Example 7

To a solution of cyclopentyl methyl ether (0.7775 g) Lignin typeA2-Ac-ester (0.1027 g) was added. The suspension was stirred underheating (70° C.). A solution comprising <12 weight % of Lignin typeA2-Ac-ester was attained.

Example 8

To a solution of 1,3-propanediol (1.5005 g) Lignin type A2-Ac-ester(0.1063 g) was added. The suspension was stirred under heating (70° C.).A solution comprising <7 weight % of Lignin type A2-Ac-ester wasattained.

Example 9

To a solution of 1,3-dioxolane (0.0905 g) Lignin type A2-Ac-ester(0.1043 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 54 weight % of Lignin typeA2-Ac-ester was attained.

Example 10

To a solution of dipropylene glycol (0.1142 g) Lignin type A2-Ac-ester(0.1038 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 48 weight % of Lignin typeA2-Ac-ester was attained.

Example 11

To a solution of dipropylene glycol (0.1631 g) Lignin type A2-Ac-ester(0.1057 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 39 weight % of Lignin typeA2-Ac-ester was attained.

Example 12

To a solution of 1,4-dioxane (0.0772 g) Lignin type A2-Ac-ester (0.0987g) was added. The suspension was stirred under heating (70° C.). Apourable solution at 70° C. comprising 56 weight % of Lignin typeA2-Ac-ester was attained.

Example 13

To a solution of methanol (0.0693 g) Lignin type A2-Ac-ester (0.0986 g)was added. The suspension was stirred under heating (70° C.). A pourablesolution at 70° C. comprising 59 weight % of Lignin type A2-Ac-ester wasattained.

Example 14

To a solution of isopropanol (0.9031 g) Lignin type A2-Ac-ester (0.1064g) was added. The suspension was stirred under heating (70° C.). Asolution comprising <11 weight % of Lignin type A2-Ac-ester wasattained.

Example 15

To a solution of dimethylsulfoxide (0.0995 g) Lignin type A2-Ac-ester(0.1034 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 51 weight % of Lignin typeA2-Ac-ester was attained.

Example 16

To a solution of tetrahydrofuran (0.0856 g) Lignin type A2-Ac-ester(0.1063 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 55 weight % of Lignin typeA2-Ac-ester was attained.

Example 17

To a solution of pyridine (0.1008 g) Lignin type A2-Ac-ester (0.1080 g)was added. The suspension was stirred under heating (70° C.). A pourablesolution at 70° C. comprising 52 weight % of Lignin type A2-Ac-ester wasattained.

Example 18

To a solution of acetic acid (0.0887 g) Lignin type A2-Ac-ester (0.0986g) was added. The suspension was stirred under heating (70° C.). Apourable solution at 70° C. comprising 53 weight % of Lignin typeA2-Ac-ester was attained.

Example 19

To a solution of hexanoic acid (1.1881 g) Lignin type A2-Ac-ester(0.1080 g) was added. The suspension was stirred under heating (70° C.).A solution comprising <8 weight % of Lignin type A2-Ac-ester wasattained.

Example 20

To a solution of isophorone (0.0835 g) Lignin type A2-Ac-ester (0.1021g) was added. The suspension was stirred under heating (70° C.). Apourable solution at 70° C. comprising 55 weight % of Lignin typeA2-Ac-ester was attained.

Example 21

To a solution of mesityl oxide (0.0670 g) Lignin type A2-Ac-ester(0.1025 g) was added. The suspension was stirred under heating (70° C.).A pourable solution at 70° C. comprising 60 weight % of Lignin typeA2-Ac-ester was attained.

Example 22

To a vial containing Lignin type A2 (0.2079 g) 1-methylimidazole (0.020g), acetic anhydride (0.2046 g), and a mixture comprising free fattyacids (0.2977 g) was added. The suspension was stirred under heating(100° C., 24 h). A pourable solution at 70° C. comprising 28 weight % ofLignin type A2 was attained.

Example 23

To a vial containing Lignin type A2 (0.1932 g) 1-methylimidazole (0.020g), acetic anhydride (0.2028 g), and a mixture comprising free fattyacids (0.4341 g) was added. The suspension was stirred under heating(100° C., 24 h). A pourable solution at 70° C. comprising 23 weight % ofLignin type A2 was attained.

Example 24

To a suspension comprising free fatty acids and Lignin type C lignin(0.1084 g) acetic anhydride as well as 1-methylimidazole (2 drp) wasadded. The suspension was stirred under heating (70° C., 1 h). Asolution comprising 10 weight % Lignin type C was attained.

Example 25

To a suspension of gas oil and Lignin type C lignin (0.0995 g) aceticanhydride, a mixture comprising free fatty acids as well as1-methylimidazole (2 drp) was added. The suspension was stirred underheating (70° C., 1 h). A solution comprising 9 weight % Lignin type Cwas attained.

Example 26

To a solution of gas oil (0.0584 g) Lignin type A2-Myr-ester (0.0195 g)(Myr is a C14 fatty acid) was added. The suspension was stirred underheating (70° C.). A pourable solution at 70° C. comprising 25 weight %of Lignin type A2-Myr-ester was attained.

Example 27

To a solution of hexanoic anhydride (0.9108 g) and 1-methylimidazole(0.0160 g) Lignin type A1 (0.407 g) was added. The suspension wasstirred under heating (120° C.) for 2 h forming an esterified lignin.Upon cooling a solution comprising 30.9 weight % of Lignin type A1 wasattained. The solution was then dissolved in a mixture of fatty acidderived from biomass in a 1:1 ratio yielding a solution comprising 15weight % of Lignin type A1.

Example 28

To a solution of hexanoic anhydride (0.4 g) and a mixture comprisingfatty acids (0.4 g) derived from biomass, Lignin type A2 (0.4 g) wasadded, as well as two drops of 1-methylimidazole. The suspension wasstirred under heating (120° C.) for 2 h forming an esterified lignin. Apourable solution at 70° C. comprising 33 weight % of Lignin type A2 wasattained.

Example 29

To a solution of acetic anhydride (0.2060 g) and a mixture comprisingfatty acids (0.2278 g) derived from biomass, the Lignin type A2 (0.2034g) was added, as well as two drops of 1-methylimidazole. The suspensionwas stirred under heating (100° C.) for 24 h. A pourable solution at 70°C. comprising 32 weight % of Lignin type A2 was attained.

Example 30

To a solution of hexanoic anhydride (0.2040 g) and a mixture comprisingfatty acids (0.2189 g) derived from biomass, Lignin type A2 (0.2007 g)was added, as well as two drops of 1-methylimidazole. The suspension wasstirred under heating (100° C.) for 24 h. A pourable solution at 70° C.comprising 32 weight % of Lignin type A2 was attained.

Example 31

To a solution of ethyl acetate (0.1398 g) Lignin type A3 (0.0961 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 41 weight % of Lignin type A3 was attained.

Example 32

To a solution of acetone (0.0885 g) Lignin type A3 (0.1038 g) was added.The suspension was stirred under heating. A pourable solution at 70° C.comprising 54 weight % of Lignin type A3 was attained.

Example 33

To a solution of polyethylene glycol (1.3309 g) Lignin type A3 (0.1021g) was added. The suspension was stirred under heating. A pourablesolution at 70° C. comprising <7 weight % of Lignin type A3 wasattained.

Example 34

To a solution of 2-methyltetrahydrofuran (0.1085 g) Lignin type A3(0.1013 g) was added. The suspension was stirred under heating. Apourable solution at 70° C. comprising 48 weight % of Lignin type A3 wasattained.

Example 34

To a solution of cyclopentyl methylether (0.1124 g) Lignin type A3(0.0996 g) was added. The suspension was stirred under heating. Apourable solution at 70° C. comprising 47 weight % of Lignin type A3 wasattained.

Example 35

To a solution of 1,3-dioxolane (0.0967 g) Lignin type A3 (0.1006 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 51 weight % of Lignin type A3 was attained.

Example 36

To a solution of furfural (0.1727 g) Lignin type A3 (0.1040 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 38 weight % of Lignin type A3 was attained.

Example 37

To a solution of dipropylene glycol (0.2092 g) Lignin type A3 (0.1032 g)was added. The suspension was stirred under heating. A pourable solutionat 70° C. comprising 33 weight % of Lignin type A3 was attained.

Example 38

To a solution of 1,4-dioxane (0.1260 g) Lignin type A3 (0.0969 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 43 weight % of Lignin type A3 was attained.

Example 39

To a solution of methanol (0.1022 g) Lignin type A3 (0.1044 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 51 weight % of Lignin type A3 was attained.

Example 40

To a solution of isopropanol (0.0775 g) Lignin type A3 (0.0955 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 55 weight % of Lignin type A3 was attained.

Example 41

To a solution of dimethyl sulfoxide (0.2907 g) Lignin type A3 (0.1037 g)was added. The suspension was stirred under heating. A pourable solutionat 70° C. comprising 26 weight % of Lignin type A3 was attained.

Example 42

To a solution of tetrahydrofuran (0.1065 g) Lignin type A3 (0.0974 g)was added. The suspension was stirred under heating. A pourable solutionat 70° C. comprising 48 weight % of Lignin type A3 was attained.

Example 43

To a solution of pyridine (0.1183 g) Lignin type A3 (0.0993 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 46 weight % of Lignin type A3 was attained.

Example 44

To a solution of acetic acid (0.1460 g) Lignin type A3 (0.1014 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 41 weight % of Lignin type A3 was attained.

Example 45

To a solution of hexanoic acid (0.1527 g) Lignin type A3 (0.1040 g) wasadded. The suspension was stirred under heating. A pourable solution at70° C. comprising 41 weight % of Lignin type A3 was attained.

Example 46

To a mixture (0.2077 g) mainly comprising fatty acid derived frombiomass, Lignin type A3 (0.0927 g) was added. The suspension was stirredunder heating. A pourable solution at 70° C. comprising 31 weight % ofLignin type A3 was attained.

Example 47

Anhydride of Tall Oil Fatty Acids.

To tall oil fatty acids (10.00 g, 1 eq) in dichloromethane (20 ml) wasadded dicyclohexylcarbodiimide (4.13 g, ca 0.5 eq) in one portion. Thereaction was stirred under argon at room temperature for 6 h, followedby addition of pentane (20 ml), filtering and washing the solids withpentane (15 ml). The clear liquids were combined and solvent wasevaporated to give 10.66 g of crude anhydride of tall oil fatty acids asthick slightly yellow oil.

Example 48

Acetic Acid Ester.

To a stirred suspension of Lignin type A2 (5.00 g) and acetic anhydride(50 ml) pyridine (50 ml) was added in two portions. The atmosphere wasreplaced by argon and stirring was continued overnight at roomtemperature. Solution was cooled in ice bath and cold methanol (150 ml)was added. After evaporating the solvent, the residue was co-evaporatedseveral times with toluene until solid material was obtained. Theresidue was dissolved in dichloromethane and precipitated with heptane.The clear solution was decanted, the solids were powdered and driedthoroughly in a desiccator under high vacuum over KOH to give 6.89 g ofthe acetyl ester as brown powder.

Example 49

Lauric Acid Ester.

Lignin type A2 (1.00 g, 1 equivalent), lauric anhydride (4.25 g, 2 eq)and dioxane (10 ml) were stirred under argon and 1-methylimidazole (0.1ml) was added. The reaction was continued at 80° C. overnight. Aftercooling to room temperature the liquid was poured into vigorouslystirred water (130 ml). The liquid was decanted and the residue wasredissolved in tetrahydrofuran and the product was precipitated withwater. The decantation and the precipitation were repeated once more.The crude product was dried, redissolved in chloroform and adsorbed oncelite (32 g). After thorough drying the solids were stirred withaqueous 0.5 M solution of NaHCO₃ (400 ml) overnight under argon. Thistreatment transformed free carboxylic acid to its corresponding sodiumsalt having higher affinity to celite than lignin ester. In some casesit was required to add tetrahydrofuran until solids were wetted toensure faster neutralisation of the free acid.

The celite with adsorbed product was filtered, washed with water anddried under vacuum. The ester was washed off with hexane to give 1.32 gof the lauric acid ester as brown residue after evaporation of thesolvent.

Example 50

Caproic Acid Ester.

According to the general procedure of esterification (see Example 49),with modifications, following amounts were used: Lignin type A2 (1.00 g,1 eq), caproic anhydride (12.8 ml, 2 eq.), 1-methylimidazole (0.44 ml,0.2 eq.) and dioxane (30 ml). A part of the product was precipitated bypouring into hexane (500 ml) under sonication. The solids were filtered,redissolved in dioxane (10 ml) and poured into hexane (200 ml). Theprecipitation was repeated once more to give 4.41 g of hexanoicanhydride ester as yellowish powder.

The dark brown supernatants after precipitation were combined, suspendedwith celite (100 g) and solvent was evaporated thoroughly. To theobtained powder was added aqueous 0.5 M solution of NaHCO₃ (800 ml) andthe resulting suspension was stirred under argon overnight. Afterfiltering the solids, washing with water and drying under vacuum theremaining ester was washed off with tetrahydrofuran:hexane 1:1 to give3.26 g of brown residue after evaporation of the solvents. This productwas combined with the ester isolated after hexane precipitation,dissolved in 20 ml dioxane and freeze dried to give 7.24 g of hexanoicacid ester as light brown sponge.

Example 51

Cis-3-Hexenoic Acid Ester.

Same procedure as for caproic acid ester, except that following amountswere used: Lignin type A2 (1.00 g, 1 eq.), cis-3-hexenoic acid anhydride(2.34 g, 2 eq.), 1-methylimidazole (0.1 ml) and dioxane (10 ml). Theprecipitation afforded 1.22 g of the ester. Subsequent purification ofthe precipitation supernatants by celite (20 g) and a solution of NaHCO₃(200 ml) as described in caproic acid ester synthesis afforded 0.2 g ofbrown residue. Combination of these two fractions of products and freezedrying from 10 ml dioxane afforded 1.4 g of cis-3-hexanoic acid ester asbrown solid.

Example 52

Myristic Acid Esters.

Partial substitutions: According to the general procedure ofesterification, following amounts were used: Lignin type A2 (1.00 g, 1eq), myristic anhydride (0.24 or 0.73 g, 0.1 or 0.3 eq),1-methylimidazole (0.1 ml) and dioxane (5 ml). After the reaction theesters were purified according to procedures below.

Example 53

Purification Procedure of Partially Substituted Esters:

0.1-eq reaction was poured into hexane (50 ml) under sonication. Afterfiltering, the solids were redissolved in dioxane (5 ml) andprecipitation was repeated once more to give 1.12 g of the ester asbrown powder. 0.3-eq reaction was worked up in the same way to give 1.23g of the ester as brown powder. Generally 1-3 precipitations weresufficient for all partially substituted esters to give a product freefrom the carboxylic acid. The presence of free carboxylic acid wasmonitored using TLC on silica-coated plates using hexane:ethylacetate:acetic acid as the eluent.

In some cases centrifuge was used to separate solid product.

Example 54

Stearic Acid Esters.

Full substitution: According to the general procedure of esterification,following amounts were used: Lignin type A2 (1.00 g, 1 eq), stearicanhydride (6.12 g, 2 eq), 1-methylimidazole (0.1 ml) and dioxane (15ml). For purification, celite (50 g) was used with 0.5 M solution ofNaHCO₃ (400 ml). Some tetrahydrofuran was added to wet the celite. Theester was washed off with neat hexane to give 1.97 g of stearic acidester as a brown solid.

Partial substitutions: According to the general procedure ofesterification, following amounts were used: Lignin type A2 (1.00 g, 1eq), stearic anhydride (0.31 or 0.92 g, 0.1 or 0.3 eq),1-methylimidazole (0.1 ml) and dioxane (10 ml). After the reaction theesters were purified according to the general purification of partiallysubstituted esters. 0.1 and 0.3-eq reactions afforded 1.12 g and 1.01 grespectively of the corresponding esters as brown powders.

Example 55

Oleic Acid Esters.

Full substitution: According to the general procedure of esterification,following amounts were used: Lignin type A2 (1.00 g, 1 eq), oleicanhydride (6.08 g, 2 eq), 1-methylimidazole (0.1 ml) and dioxane (10ml).

The product was purified by dissolving in chloroform and washing withwater followed by celite purification. For further purification celite(50 g) was used with 0.5 M solution of NaHCO₃ (400 ml). The ester waswashed off with neat hexane to give 2.49 g of oleic acid ester as brownthick oil.

Partial substitutions: According to the general procedure ofesterification, following amounts were used: Lignin type A2 (1.00 g, 1eq), oleic anhydride (0.30 or 0.91 g, 0.1 or 0.3 eq), 1-methylimidazole(0.1 ml) and dioxane (10 ml). After the reaction the esters werepurified according to the general purification of partially substitutedesters. 0.1 and 0.3-eq reactions afforded 1.13 g and 1.18 g respectivelyof the corresponding esters as brown powders.

Example 56

Behenic Acid Esters.

Full substitution: According to the general procedure of esterification,following amounts were used: Lignin type A2 (1.00 g, 1 eq.), behenicanhydride (7.37 g, 2 eq.), 1-methylimidazole (0.1 ml) and dioxane (20ml). The product was purified by dissolving in chloroform and washingwith water followed by celite purification. For further purification,celite (50 g) was used with 0.5 M solution of NaHCO₃ (400 ml).

Some tetrahydrofuran was added to wet the celite. The ester was washedoff with hexane:tetrahydrofuran 1:1 to give 2.62 g of behenic acid esteras a brown solid.

Partial substitutions: According to the general procedure ofesterification, following amounts were used: Lignin (1.00 g, 1 eq),behenic anhydride (0.37 or 1.11 g, 0.1 or 0.3 eq), 1-methylimidazole(0.1 ml) and dioxane (10 ml). After the reaction the esters werepurified according to the general purification of partially substitutedesters. 0.1 and 0.3-eq reactions afforded 1.15 g and 1.20 g respectivelyof the corresponding esters as brown powders.

Example 57

Erucic Acid Esters.

Full substitution: According to the general procedure of esterification,following amounts were used: Lignin type A2 (1.00 g, 1 eq.), erucicanhydride (5.49 g, 1.5 eq.), 1-methylimidazole (0.1 ml) and dioxane (15ml). The product was purified by dissolving in chloroform and washingwith water, followed by celite purification. For further purification,celite (50 g) was used with 0.5 M solution of NaHCO₃ (400 ml). Sometetrahydrofuran was added to wet the celite. The ester was washed offwith hexane to give 2.57 g of erucic acid ester as brown thick oil.

Partial substitutions: According to the general procedure ofesterification, following amounts were used: Lignin type A2 (1.00 g, 1eq), erucic anhydride (0.37 or 1.10 g, 0.1 or 0.3 eq), 1-methylimidazole(0.1 ml) and dioxane (10 ml). After the reaction the esters werepurified according to the general purification of partially substitutedesters. 0.1 and 0.3-eq reactions afforded 1.13 g and 1.17 g respectivelyof the corresponding esters as brown powders.

Example 58

Tall Oil Fatty Acid Ester.

According to the general procedure of esterification, following amountswere used: Lignin type A2 (1.00 g, 1 eq.), anhydride of tall oil fattyacids (5.36 g, ca 2 eq.), 1-methylimidazole (0.1 ml) and dioxane (10ml). Product was purified by dissolving in chloroform and washing withwater. For further purification, celite (50 g) was used with 0.5 Msolution of NaHCO₃ (400 ml). The ester was washed off with hexane togive 3.91 g of tall oil fatty acid ester as brown thick oil.

Example 59

Solubility of Lignin Esters in Different Carrier Liquids

The solubility was evaluated by adding ˜100 mg of lignin or esterifiedlignin to a HPLC vial followed by the addition of a small amount ofsolvent or carrier liquid (˜3 drops or less). The vial was then put in ashaker at 70° C. and 900 rpm for about 1 h. If the lignin was notdissolved and pourable at 70° C. then more solvent or carrier liquid wasadded (3 drops or less) and put on shaker for a further 30 min. Thefinal step was repeated until the mixture was pourable at 70° C. or thevial being full. The results are present in FIGS. 1, 2A and 2B. Theesterified lignins of FIG. 1 have not been purified while the esterifiedlignins of FIGS. 2A and 2B have either been precipitated in hexane orpurified using Celite.

(EA=ethyl acetate, EtOH=ethanol, MeTHF=methylated tetrahydrofuran,CPME=cyclocpentyl methyl ether, iPrOH=iso-propanol, RTD=tall oil,LGO=light gas oil, CF=membrane filtered lignin, LGTPA=acid precipitatedlignin from black liquor dried to 95% dry weight and GM63=ligninchemically reduced using the method according to WO2012/121659)

Example 60

Esterification with TiO(acac)₂

Lignin type A2 (0.5 g), oleic acid (1.5 g) and TiO(acac)₂ (50 mg, 10 wt%) was added to a round bottom flask in a distillation setup. Themixture was initially heated under stirring to 140° C. overnight. Thefollowing night the reaction was continued but with vacuum (>50 mbar)applied and 140° C. The following night the reaction was continued withvacuum but at 180° C. The reaction was followed by GPC, FIG. 3.

Example 61

Esterification with Fe(acac)₃

Lignin type A2 (180 mg, 1.00 mmol), oleic acid (894 mg, 3.17 mmol) andFe(acac)₃ (35 mg, 0.10 mmol) was added to a round bottom flask in adistillation setup. The mixture was heated under stirring and vacuum to180° C. for 30 h. The experiment was repeated and heated under vacuumfor 3 days. See FIG. 4.

Example 62

Conversion of the Composition into Diesel Fuel

A composition according to the present invention comprising 100%esterified lignin in RTD and LGO was treated in a hydrotreater. Theobtained product remained well into EN590 specifications for roaddiesel.

Example 63

Up-Scaled Preparation

Lignin type A2 was extracted using iso-propanol. The isolated extractedlignin (15 kg) was esterified using oleic acid (64 kg), Ac₂O (Aceticanhydride) (48 kg) and 1-methylimidazole (2.6 kg) according topreviously described method. The Ac₂O and imidazole was distilled offand a composition of 19% lignin in oleic acid was obtained.

Example 64

300 g of the esterified lignin of Example 63 was mixed with 200 ml ofhot methanol and 300 mg of Dowex 2X and heated over night at 80° C. Theexcess MeOH was evaporated and the rest was dissolved in 300 mL hexaneand filtered. Hexane was evaporated and the formulation was analysedaccording to the rest of carboxylic acids (HMBC).

The esterification of the fatty acid was confirmed using GPC and NMR.

Example 65

300 g of the Lignin type A2 was mixed with 200 ml of hot methanol and300 mg of Dowex 2X and heated over night at 80° C. The excess MeOH wasevaporated and the rest was dissolved in 300 mL hexane and filtered.Hexane was evaporated and the formulation was analysed according to therest of carboxylic acids (HMBC).

The esterification of the fatty acid was confirmed using GPC and NMR.

Example 66

A mixture of organosolv lignin (28 mg, 1 eq, 0.156 mmol), oleicanhydride (170 mg, 2 eq, 0.311 mmol), dioxane (1 ml) and1-methylimidazole (1 drop) was heated with stirring at 80° C. underargon for 22 h. The reaction was cooled and solvent removed under vacuumto give 202 mg of organosolv ester as a clear orange-yellow oil. Theproduct was miscible with hexane, LGO and RTD.

The invention claimed is:
 1. A composition comprising a carrier liquidand lignin or lignin derivatives solubilized in said carrier liquid;wherein the hydroxyl groups of the lignin or lignin derivatives havebeen substituted with ester groups forming esterified lignin or ligninderivatives and wherein the degree of substitution is more than 30%,wherein the ester groups are C8 or longer groups and wherein the amountof the esterified lignin or lignin derivative in composition is 1 weight% or more; and wherein the carrier liquid is a gas oil.
 2. Thecomposition according to claim 1 wherein the amount of the esterifiedlignin or lignin derivatives in the composition is 2 weight % or more.3. The composition according to claim 1 wherein the hydroxyl groups ofthe lignin has been substituted to a degree of substitution of 40% ormore.
 4. The composition according to claim 1 wherein the lignin orlignin derivative has a weight average molecular weight of not more than2,000 g/mol.
 5. The composition according to claim 1 wherein the carrierliquid is light gas oil (LGO).
 6. The composition according to claim 1wherein the hydroxyl groups of the lignin or lignin derivatives havebeen substituted with ester groups of an unsaturated fatty acid.
 7. Thecomposition according to claim 1 wherein the composition comprises 20weight % or more of the carrier liquid.
 8. The composition according toclaim 1 wherein composition comprises at least 40 wt % of the carrierliquid and wherein the amount of the esterified lignin or ligninderivatives in the composition is at least 2 wt %.
 9. A method formaking fuel by treating the composition according to claim 1 in ahydrotreater or a catalytic cracker.
 10. A fuel obtained from thecomposition according to claim
 1. 11. A lubricant obtained from thecomposition according to claim
 1. 12. A method of preparing thecomposition according to claim 1 wherein the method comprises the steps:a. providing a gas oil, and lignin or lignin derivatives; b. providing aC8 or longer esterification agent and optionally a catalyst; c. mixingthe components of step a and b to form a slurry; d. heating the mixture;and e. letting the components react in order to form a homogenouscomposition of esterified lignin or lignin derivatives in a gas oil. 13.The method according to claim 12 wherein esterification agent is ananhydride.
 14. The method according to claim 12 wherein an imidazole oran acid is added as a catalyst.
 15. The method according to claim 12wherein the mixture is heated to at least 80° C.
 16. The methodaccording to claim 12 wherein the mixture is heated to at least 120° C.17. The composition according to claim 1 wherein the amount of theesterified lignin or lignin derivatives in the composition is 10 weight% or more.
 18. The composition according to claim 1 wherein the amountof the esterified lignin or lignin derivatives in the composition is 20wt % or more.
 19. The composition according to claim 1 wherein thehydroxyl groups of the lignin has been substituted to a degree ofsubstitution of 60% or more.
 20. The composition according to claim 1wherein the hydroxyl groups of the lignin has been substituted to adegree of substitution of 80% or more.
 21. The composition according toclaim 1 wherein the hydroxyl groups of the lignin has been substitutedto a degree of substitution of 99% or more.
 22. The compositionaccording to claim 1 wherein the hydroxyl groups of the lignin has beensubstituted to a degree of substitution of 100%.
 23. The compositionaccording to claim 1 wherein the composition comprises 40 weight % ormore of the carrier liquid.
 24. The composition according to claim 1wherein the composition comprises 80 weight % or more of the carrierliquid.